Despite a cameo from the original murderous moppet, this update is anything but killer.

This saccharine phrase heard in Lifetime’s “The Bad Seed” remake is a haunting holdover from Mervyn LeRoy’s classic 1956 psychological thriller. Delivered with just the right amount of false cheer by the titular murderous child Emma Grossman (McKenna Grace), the line is made even creepier because she’s actually practicing saying it in front of a mirror, followed by a calculated smile.

It’s frightening, it’s silly, and it’s exactly the type of camp that’s expected — nay, craved — from the Lifetime remake machine. Sadly, that’s the best part of the entire movie, and it was already blown in the teaser trailer

Rob Lowe executive produces and directs this update of “The Bad Seed,” in which he also stars as the gender-flipped single parent David Grossman who suspects his overachieving “honey bear” is a little off following a tragedy. For the most part, the movie is adequate in how it gradually unspools Emma’s psychopathic tendencies and David’s growing distress. But “adequate” doesn’t win medals (not the cool ones you’d want to kill for anyway), and it certainly isn’t that entertaining. In fact, it’s kind of boring.

McKenna Grace, “The Bad Seed”

Bettina Strauss/Lifetime

David is a widower who designs chairs or something like that. It really doesn’t matter what he does. He just works from home out of his garage, okay? That allows him to be on hand often but just distracted enough to need to hire someone to care for Emma when he’s not available. Enter the babysitter/nanny Chloe (Sarah Dugdale), who adds a half-hearted homewrecker vibe to the proceedings. She’s a rebel who curses and calls her employer a DILF.

Despite the superficial updates, “The Bad Seed” is surprisingly tame, even compared to the original, which was frightening for its heightened melodrama and claustrophobic setting (it was based on a play that had been adapted from William Marsh’s novel of the same name), not to mention Patty McCormack’s demented take on a homicidal child. Lifetime’s version hasn’t really been amped up for today’s audiences who are far too savvy about killer kids in movies. Either make the story scarier by allowing Emma to really dig into her sinister side, or make it campier. Since this is on Lifetime, it really should’ve gone the latter route.

Consider all the cruel and creative ways that Emma could’ve offed people or the killer puns to be had. What if Emma were some Rube Goldberg machine-building savant (the “Final Destination” writers are still around) who also liked limericks? There are so many totally batshit directions the movie could’ve gone, and Grace’s talents seem up to the task of letting Emma’s inner psychopath skip and play.

Mckenna Grace and Patty McCormack, “The Bad Seed”

Bettina Strauss/Lifetime

Fans of the original film at least get an extra dimension to their viewing experience by virtue of seeing what is different, including whether or not the ending stays true to William Marsh’s book, the 1956 version that had to meet the Motion Picture Production Code, or is its own beast entirely. In addition, a few nods are made to LeRoy’s classic, such as casting the first “Bad Seed” herself, the Oscar-nominated McCormack, as Emma’s psychiatrist.

Most baffling of all is that Lifetime’s remake gives away quite a bit in the opening sequence of images, as if to undermine its own tension and surprises. This is not merely foreshadowing; it’s spoiling. “The Bad Seed” had the potential to have fun with a well-established but outdated story, but in the end, its lack of narrative chutzpah has led to a basket of misses.